The line mod increases shift pressure making the shifts occur faster. How it works by itself I don't know yet because when I installed it I also had a chip in changes the shifting also. But I can say my truck loudly barks the tires on the 1-2 shift and chirps them on the 2-3 shift. And that it never did prior to chip/line mod.

Install

First and formost = OH HELL IS THIS A MESSY JOB. It stinks and it's a mess. When I installed my line mod I also put on a 4x4 tranny pan and new filter, which makes the mess a little less. The stock tranny pan doesn't have a drain, so it must be dropped everytime the fluid needs to be changed. The 4x4 has a drain plug, and thats why I put it on.

First thing, jack up the front of the truck and place on jack stands.

Since I was putting in a new pan, I drilled a few holes in the old pan to release as much trans fluid as possible.

Once the fluid is done draining remove all the bolts and drop the pan. Be carefull as it still has some fluid in it.

Clean of the gasket and set that and the srews aside.

Next pull down and tug on the filter gently, it has more transfluid in so try and get as much of that out as possible. Then remove the filter.

Next unbolt the accumulater and carefully slowly and remove it. The is another little filter that will 99% of the time fall out as well. Carefully note how and where this goes so when you put it back it's put back properl.

In the corner is a little clip that holds the line mod, remove the clip and tap the accumulator a little to get the line mod out. Once it pops out just swap it with the new and make sure the spring is in there. Replace the clip(sorry no pics)

Put the accumulator back on, and make sure the small filter is the correct place you saw it come from earlier.

Bolt the accumulator back on and torque it down to 14lbs per INCH.

Put the new filter in.

Put the 4x4 pan on with the old gasket, and make sure to remove the magnet from the old pan and place it around the drain plug of the 4x4 pan.

Bolt the 4x4 pan down good.

Fill up the trans with fluid.

Start the truck and let it run for a minute or 2, then go in reverse/drive a few times. Check the fluid and add as needed.

Take the truck for a quick drive, then check the fluid again and fill as needed.

Take the truck for another spin, WOT and listen for the tire screetching on the shift.